Process of making bituminous material



Patented Jan. 17, 1933 UNITED STATES PATENT OFFICE HARRY O. NEUBERGER, OF NEW YORK, N. Y., ASSIGNOR T NEUBERGER CHEMICAL COR- PORATION OF NEW YORK, 1ST. Y., A CORPORATION OF DELAWARE PROCESS OF MAKING BITUMINOUS MATERIAL No Drawing.

This invention relates to an improved coldlaid bituminous material and the process for making the same, which material is adapted for use in surfacing roadways, sidewalks and 5 the like, and belongs more particularly to that class of paving materials which consist broadly of the combination of a bituminous or asphaltic binder with a mineral aggregate.

It is well known that the so-called natural rock asphalts have been mined and used extensively. as paving materials for forming roadway surfaces. It is also well known that thees natural rock asphalts all contain a bituminous binder material mixed with a ineral aggregate, the character of the mineral aggregate varying in different localities from a more or less friable limestone to a hard, fiinty or silicious material. These natural rock asphalts are characterized in general by the fact that the particles as freshly mined do not readily cohere but form a granular or crumbly mass which may be readily handled and uniformly spread upon a road surface when cold with a shovel or other implement. When such material is laid cold and spread upon a roadway surface and then subjected to pressure, however, the particles tend to unite with each 39 other to form a firm, compact surface which does not wave or creep under summer heat, and which is less subject to cracking or disintegration in cold weather and under heavy traffic than the artificially formed paving materials now in use. Those natural rock asphalts which contain a silicious mineral compound of hard sand provide a particularly firm and efficient paving material for roads and the like, as the mineral particles do not become broken and are capable of withstanding the destructive effects of heavy trafiic more completely than the artificially formed paving material now in use. Heretofore, it has been impossible to make by artificial means a paving material which in its practical operation possesses the advantages of the natural rock asphalts which have silicious mineral matter incorporated with the r bituminous binder. One object of the present invention is to Application filed August 6, 1929. Serial No. 383,983.

provide a bituminous paving material which closely resembles both in the relative proportions of bitumens and mineral aggregate contained therein, as well as in its physical characteristics, those natural rock asphalts which comprise a bituminous binder having incorporated therein a hard silicious mineral aggregate, and the novel method of producing such material.

A further object of the invention is to pro- .0 vide an improved process for readily making a bituminous paving material which in its initial condition and before being laid as a pavement is of a somewhat loose and granu- I lar character whereby it may be readily han- 5 died and easily spread upon the surface of the roadway, while at the same time it may be readily compacted by pressure to form a firm and compact road surface which will not crack, wave or spread under the influence of heat and heavy trailic, and will not break down or disintegrate in cold weather.

Another object of the invention is to provide a simple and efiicient process for making a bituminous material of the character described whereby the material may be so prepared and the mineral particles thoroughly coated with the bituminous binder at a relatively low temperature so that the bitumen content of the mass is not injured by the application of great heat, and wherein the finished material is cooled while agitated to produce a loose granular mass so conditioned as to be capable of being readily handled and spread, while application of pressure thereto produces a coherent and firm pavement sur face adapted to support traflic under all conditions.

A further object of the invention is to provide an improved bituminous material containing a suitable proportion of heavy hydrocarbon oils mixed with the bitumen to promote the pliability of the paving material and prevent its early deterioration.

Other objects and advantages of the invention relate to various improved steps and arrangement of steps in the process of manufacture of the material as will be more fully set forth in the detailed description to follow.

In carrying out the improved process it is proposed to employ a bituminous matter which comprises bitumen or asphalt, combined with a mixture of heavy oils such as are present in a crude petroleum having an asphaltic base and from which the more volatile elements have been removed by distillation. The term bitumen as used herein 1s employed to designate a natural asphalt or a petroleum residue from which both the light and heavy oils have been substantially completely removed, or any suitable mixture of these materials while the term bituminous binder or bituminous binder material as used herein designates the product obtained by incorporating in such bitumen a sufficient amount of crude petroleum or heavy oils havin an asphaltic base as to insure aproper mixture of the bitumen and heavy ethereal oils for imparting the desired degree of pliability to the bituminous binder and preventing its early deterioration through loss of those heavy oils which are present therein in its natural state.

This bituminous binder material may be prepared from a natural asphalt or from bitumen or both by adding thereto a crude petroleum from which the volatile elements have been removed by topping or by adding thereto heavy petroleum oils having an asphaltic base. By heavy petroleum oils is meant those heavy, high boiling point hydr carbon oils which remain after the petroleum has been subjected to fractional distillation to remove its more volatile constituents. The bituminous binder material may be a petroleum residue having an asphaltic base and which contains at least 7 5% of asphalt and 25% of petroleum oils, such for example as Penuca oil. Whether the bituminous binder material is prepared by adding crude petroleum or heavy oils to asphalt or bitumen or both, or whether a residue containing a large proportion of asphalt and a lesser proportion of heavy oils is employed the bituminous binder material when ready for use contains in either case a very large percentage of asphalt or bitumen, combined with a small percentage of those asphaltic base petroleum oils which hzwe a high boiling point and are not removed by the topping operation and which combine with the asphalt or bitumen to give the material the 7 desired fluidity and serve as a lubricating agent and preservative for the bitumen so that the bituminous binder material when combined with the mineral aggregate will possess the necessary plasticity to permit the finished materials to be readily handled and spread as well as to prevent early deterioration of the final material such as would result if asphalt or bitumen uncombined with the heavier hydrocarbon oils was employed. The heavier petroleum oils as added to the asphalt in the form of crude petroleum oras present in the Penuca oil also acts as a partial solvent for the asphalt to effect a quick and complete coating of each mineral particle with the bituminous binder mate rial. This bituminous binder as it is present in the completed product should not contain any substantial proportion of the lighter volatile hydrocarbons, such as gasoline, benzene, and the like, as the presence of these lighter hydrocarbons will tend to render the bituminous binder material unduly soft, thus causing the final product to congeal unduly, and their presence would result in breaking down the coating which the bituminous binder material is intended to form around each mineral particle.

By the addition to the asphalt or bitumen of the heavier petroleum oils or ethereal oils as above described there is incorporated in the bitumen a certain proportion of those heavy oils of the same or similar character to those heavy oils which are removed from the bitumen in the final stages of its separation from petroleum. double purpose of rendering the bitumen more fluid for use at relatively low temperatures in coating the mineral particles and also act as lubricants or preservatives to prolong the life qualities of the bitumen content of the finished material. The proportion of heavy oils which are added to the asphalt or bitumen or which are associated therewith in such petroleum residues as Penuca oil These oils serve the may vary somewhat dependent upon the temperatures to which the bituminous binder material is to be raised in mixing the mineral aggregate therewith as well as the character of the oils initially present in or added to the bitumen.

If the mineral aggregate is to be coated at relatively low temperatures, as is desirable to prevent injury to the bitumen content of the material, a somewhat larger proportion of heavy oils should be employed than would be required in carrying out the mixing operation at higher temperatures, and larger proportions of the oils may be required if the oils contain a considerable quantity of the lighter hydrocarbons which are to be driven off in heating the combined material in vacuo. In general it is regarded as preferable that the heavy oils added to or present in combination with the bitumen be equal to from 8% to 25% of the bitumen by weight, although I am aware that these limits may be varied in some cases, and consequently set them forth herein for the purpose of illustration rather than as absolute limitations to bestrictly followed in all cases.

The mineral aggregate which is to be incorporated in the bituminous binder material may vary somewhat dependent upon the use for Which it is to be employed. Preferably the mineral aggregate is a hard silicious or stone material, free from lime or limestone,

and itmay be sand, crushed rock, orsandstone which will meet the necessary tests as to its crushing strength. It is desirable that lime or limestone be excluded from the mineral aggregate since the presence of lime tends to harden the bitumen content of the material and thus render the final product undul hard and brittle. When the material is to e used as a surfacing for road and the like, the mineral aggregate is preferably formed from fine, hard silica sand which may be of such size as to pass through a sieve of from l0200 mesh to the inch. lVhen the final material is to be employed as subsurfacing for roadways and the like, a part or all of the mineral particles may be from A; to inch in diameter, and this coarser aggregate may be used alone or may be mixed with a more finely divided mineral material, such, for example, as the line sand previously described. In either case it is preferred that the mineral matter be in the form of hard, sharp sand or stone particles which will not brealr or fracture under the wei ht of heavy loads and which may be thoroughly coated with the bituminous binder material.

The bituminous binder and mineral aggregate may be combined in various ways to form the completed material,dependent upon the moisture content of the mineral aggregate and the manner in which it may be considered desirable to remove the moisture and cite/ct the coating of the particles. In this operation it is necessary to substantially entirely remove the moisture content of the mineral aggregate and effect a complete coating of each mineral particle with the bituminous binder.

This operation may be carried out by first incorporating in the bituminous binder material as above described a suitable quantity of a hydrocarbon solvent such as benzol to render the bituminous binder material fairly liquid and then adding the mineral aggregate from which the moisture has not been removed, and agitating the mass to thoroughly mix the mineral aggregate with the more fluid bituminous binder material. This mixing step may be carried out in either an open or a closed chamber, but for the purposes of economy it may well be carried out in the closed chamber in which the mixture is to be heated for eliminating the added solvents and the moisture contained in the mineral aggregate. After the completion of the miring operation the combined material is heated in a closed chamber. the chamber being preferably provided with means for agitating the mass during the heating operation. The closed chamber is subjected to a vacuum of from 20 to 28 inches and the material is heated to a temperature of to degrees F. to remove the moisture content of the mineral aggregate and the benzol solvent. As the material is heated under vacuum the of the moisture and solvent. The use of vacuum as above described permits the removal or" the moisture content of the mineral aggregate as well as the solvent material at a much lower temperature than would be otherwise required and thus avoids injury to the bitumen by subjecting it to an unduly high temperature. In this way, also the solvent and water vapor which are driven from the material may be drawn over into a condenser and substantially all of the solvent recovered for re-use. In this method of carrying out, the operation it is preferred to employ ben- 201 as a solvent, or some other solvent having higher boiling point than water, as this insures substantially complete elimination of the moisture content of the mineral aggregate prior to the entire removal of the sol- I vent and thus insures a complete coating of each mineral particle by the bituminous binder material while in a substantially fluid state.

Another method of carrying out the mixing operation is to first completely dry the mineral aggregate before it is mixed with the solvent impregnated bituminous binder material. As in the previous case the mineral aggregate may be added to the bituminous binder material in either an open or a closed chamber, but is preferably added in the closed chamber in which the material is to be subsequently heated under vacuum, the chamber being provided with means for stirring or agitating the combined materials to insure a complete mixing of the same while being heated.

When mixing the materials in this mannor a. solvent having a lower boiling point than benzol may be employed in the place of the benzol since the moisture having already been eliminated from the mineral aggregate the necessity for using a solvent having a higher boiling point than water is no longer present,.and any suitable hydrocarbon solvent material may be employed such for example, gasoline. benzene, naptha, carbon tetrachloride xylol, or the like. As in the method previously described, the mineral aggregate and solvent impregnated bi tuminous binder material are preferably mixed together thoroughly by agitating mechanism contained in the heating chamber duringthe heating operation, and the heating chamber is subjected to a vacuum of from 20 to 28 inches during the heating and stirring operation to substantially completely remove the solvent liquid, which, as in the previous case is led to a condenser and recovered for further use. The temperature at which the heating operation is carried out may vary from 85 degrees F. to 100 degrees F. dependent upon the boiling point of the solvent liquid, but in any case the temperature required is relatively low and the use of the vacuum serves both to permit the mixing of the materials at a relatively low temperature whereby injury to the bitumen is avoided, and also insures the complete coating of each mineral particle by the bituminous binder material.

The addition of light hydrocarbon solvents to the bituminous binder material not only renders the bitumen sufficiently fluid to produce a highly effective coating of the mineral particle, but also tends to draw away with it in its removal any destructive light oils Which may be present in the bitumen. Mixing the bituminous binder and mineral aggregate in the heating chamber while agitating the mass, and while maintaining the chamber under a partial vacuum tends to bring the/bituminous binder material into intimate contact with all parts of the mineral matter and force the fluid bituminous binder between all particles of mineral matter to insure a substantially full and complete coating of each separate particle of the mineral aggregate. While I have mentioned the use of a vacuum ranging from 20 to 28 inches I prefer to employ a vacuum of from 26 to 28 inches in heating the material and removing the solvent as requiring a lower temperature than in the case of higher pressures and effecting a more rapid and complete removal of the moisture solvent liquids and higher boiling point hydrocarbons In the mixing operation it is regarded as preferable that the hydrocarbon solvent liquid be added to and mixed with the bitumen prior to the incorporation of the mineral aggregate therewith in order that the bitumen content may be rendered thoroughly an d uniformly fluid prior to the addition of the mineral aggregate whereby a thorough and uniform coating of the mineral particles may be effected without undue delay.

The heating step for the purpose of substantially entirely removing the solvent hydrocarbons as well as the moisture carried by the sand or mineral aggregate is effected at a relatively low temperature, as compared with the usual temperatures of from 250 to 45.0 degrees F., which are employed in the preparat'non of the hot-mix paving material, thus preventing injury to the bitumen or the lubricating qualities of the heavy hydro arbon employed in the mixture such as would tend to cause a hardening of the paving material and consequently effect such deterioration of the same as would destroy its resilient characteristics.

After incorporating the mineral aggregate in the bituminous binder material by either of the methods described above and heating the mass under vacuum to effect a complete coating of each particle and remove the solvent, the mass is discharged from the heating chamber and is preferably passed immediately into water in a suitable receptacle where it is continually agitated while it is being cooled by contact with the water. The agittl tlOlllOf the material in the presence of water serves to prevent the various particles from ,uniting together to form a compact mass and tends to so separate the particles as to produce a loose, granular mass which after being cooled in this way will remain in a more or less loose and granular state :while it is being transported to the place where it is to be used as a paving material. lVhile I have described the method of'simultaneously cooling the material in water and agitating same during the cooling operation as being well adapted for the purpose of properlyconditioning the material and preventing it from eongealing unduly, it is to be understood that other methods of cooling the material maybe employed such as cooling the material while stirring or otherwise agitating the same in a current of cold air, or even at room temperatures, or by any combination of air and water cooling means provided that the material is agitated, stirred or'otherwise kept in motion substantially continuously during the cooling step. The loose granular material thus formed, when agitated during the cooling operation to separate the particles and form a relatively loose granular mass, does not readily pack together an d substantially ret ains'its granular character while being transported to the place where it is to be used so that it may be easily handled and readily spread upon a road surface. After being spread upon the road surface, pressure is applied by means of a roller, in accordance with the general prac tice, which serves to compact together the bitumen coated mineral particles and form a firm surface. The substantially complete removal of the light hydrocarbon solvent to gether with the presence of a certain proportion of heavy lubricating oil in the bitumen, together with the fact that the bitumen has not been exposed to unduly high temperature during the heating results in the production of a material which possesses a high degree of resiliency and which will not be unduly softened by summer heat nor rendered brittle by the cold of winter. The material being highly resistent to the destructive effects of heavy tl'illllC and capable of withstanding extremes of temperatures.

The improved paving material is of a loose, granular character previous to its being laid upon a roadway and compacted together by rolling, and the particles do not cohere to the extent of forming a hard, rocklike mass as is the case with the usual paving material formed by the hot-mix process, nor does it require heating before being laid upon a road surface. The paving material is laid cold and after being compacted by rolling possesses a high degree of resiliency and is adapted to be further compacted by traflic without becoming broken or disintegrated. It does not set or become hard after being laid as is the case with the usual hot-mix paving materials nor those containing lime.

In heating the mixture of bituminous binder material and mineral aggregate under vacuum there is removed from the mixture any moisture which may be present in the mineral aggregate as well as the hydrocarbon solvent added to the bitumen prior to the incorporation of the mineral aggregate therein and'also such of the higher boiling point hydrocarbons as may be present in the heavy oils as added to the bitumen or in the petroleum residues employed in forming the bituminous binder.

While the main purpose for which it is intended to employ the improved bituminous material above described is for use as a surfacing or sub-surfacing for roadways, walks,

and the like, it may be used to advantage as an insulating material and in construction work generally where it may be desired to employ an insulating and waterproof material which can be readily handled and compacted by pressure.

The paving material formed in the manner above described can be laid on concrete, macadam, gravel, or an asphalt sub-surface material, and may be firmly united with such base material by first applying an asphaltic paint to the material to be covered before laying the paving material.

The relative proportions of bituminous binder and mineral aggregate which have been found best adapted for use in forming the paving material for-use as a surfacing for roadways are approximately 7% of bituminous binder material and 93% of mineral aggregate by weight. The improved paving material as formed by the present process is considerably lighter in weight than the usual asphalt paving material, one cubic yard of the present material weighing about 2160 pounds as compared with a weight of 3140 pounds for a cubic yard of the usual asphalt paving material.

While I have set forth in considerable detail the various steps employed in the process of making my improved material as well as the proportionate quantities of the constituents which have been found to be best adapted for the production of an eflicient material of the character described, it is to be underst d. that va ieu hange may bema'd n t steps f the p es a d t rderin which t e va o s Steps re car ied ou as We l a in he p p r on t the en t tu e mate ia s. me yed Wit Qu-tdera tinsfr m t e, spiri an p f my n n on s set ferth in t appende c ms which are to be roadly eeest u d in the ligh of my d closure. 1

lVli-at claim is 1. Theprocess of making a resilient cold laid paving material consisting of a hard silicious mineral aggregate and a bituminous binder material which comprises, the step of mixing the mineral aggregate and bituminous binder material by agitating the mass at a temperature of approximately 100 degrees F adding a volatile hydrocarbon to the mass prior to the mixing operation, and removing the volatile hydrocarbon from the mixed material under a vacuum in excess of twenty inches and at a temperature of approximately 100 F. prior to the completion of the mixing operation.

2. The process of making a resilient cold laid paving material consisting of a hard silicious mineral aggregate and a bituminous binder material which comprises, the step of mixing the mineral aggregate and bituminous binder material by agitating the mass at a temperature of approximately 100 F adding a volatile hydrocarbon to the mass prior to the mixing operation, removing all volatile hydrocarbon from the mixed material under a vacuum in excess of twenty inches and at a temperature of approximately 100 degrees F. prior to the completion of the mixing operation, and further agitating the mass in the presence of water after the completion of the mixing operation.

3. The process of making a pliable, resilient, cold laid paving material consisting of a hard non-calcareous mineral aggregate mixed with a bituminous binder material consisting of bitumen and heavy hydrocarbons such as remains after the completion of the popping operations which comprises, increasing the fluidity of the bituminous binder material by the addition of a volatile hydrocarbon, mixing the mineral aggregate and fluid bituminous binder material by agitating the same at a temperature of approximately 100 degrees F., and subjecting the heated material to a vacuum of from 20-28 inches to remove all volatile hydrocarbons from the mass.

4. The process of making a resilient, cold laid paving material consisting of a noncalcareous mineral aggregate united with a bituminous binder material consisting of bitumen and heavy petroleum oils, which comprises, thoroughly mixing the mineral aggregate with the bituminous binder material, adding a volatile hydrocarbon to the o signature.

bituminous binder material prior to the comletion of the mixing operation, and subecting the mixed material to a temperature of approximately 100 degrees F. and a vacuum in excess of 20 inches to remove entirely the volatile hydrocarbon from the mass prior I eration.

to the completion of the mixing 0 xed my In testimony whereof I have a HARRY C. NEUBERGER.

CERTIFICATE OF C{)RRECTW'Nv Patent No. 1,894,630. January 17, 1933.

HARRY G. NEUBERGER.

it is hereby certified that error appears Er. the printed specification of the above numbered patent requiring correction as fellows: Page 5, tine 112, claim 3, for "popping" read "topping"; and that the sadlcttcrs Patentshoulttbc read with this correction therein that the same may contorm to the record of the case it; the Patent Office.

Signed and sealed this 21st day of February, A., D. 1933.

M. J. Moore,

(Sea!) [acting Qcmmissioncr of iatcnts. 

